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[SANET-MG] escape of the transgenic zucchini
September 20, 2005
Prof. Joe Cummins
Escape of the Transgenic Zucchini
Seminis seeds, a company owned by Monsanto Corporation recently admitted
that genetically modified (GM) zucchini squash (courgettes) had been
planted in Germany, The company claims to have destroyed the crop.
Presumably, the GM zucchini was modified with viral coat protein genes
for virus resistance (virus resistance has been the only trait Seminis
Seeds incorporated into GM squash, Cucurbita pepo). Interestingly,
Seminis is along with USDA and Cornell University patentees of GM virus
resistant Papaya that was recently “accidentally” extensively planted in
Thailand polluting much of the crop. “Accidental” genetic pollution of
an existing crop could be used as a justification for rapid approval of
the release of the transgenic crop.
Squash (Cucurbita pepo) is among the four cultivated species of
Cucurbita, C. pepo, C. maxima ,C. mixa and C. moschata. These species
originated from gourds in Mexico and Central America (1). Cucurbita pepo
was domesticated about 10,000 years ago making its domestication
contemporary with maize and beans (2). Cucurbita pepo includes zucchini,
crook neck squash and pumpkins within its species. C. pepo is monecious
with male and female flowers on the same plant. The male flowers produce
heavy stick pollen that requires insect pollination but insect
pollination may transfer the pollen over a large distance(1). C. pepo
was introduced into Europe soon after the discovery of the Americas.
Currently there are a number of landraces and feral forms of C, pepo in
Europe(3) C. pepo subspecies pepo includes Zucchini, Pumkin, Vegetable
Marrow and Cocozelle, C. pepo subspecies texana includes the crookneck,
Acorn and Scallop squash (4). Most wild C. pepo are located in the
Americas (1), while feral races are commonplace in Europe (2).
There have been 68 field test applications for GM squash in the United
States , 67 of these have been for virus resistance. 17 field tests were
undertaken on virus resistant GM squash in Mexico, 9 in Egypt,3 in
Italy,2 in Spain and one in France (5).
The GM zucchini presently handled by Seminis was derived by crossing
Zucchini with GM crook necked squash developed by Asgrow Company who
received a permit for commercial release of the the squash in 1994 ( the
second GM crop approved for commercial release). Asgrow was fused with
Petoseeds to become Seminis in 1995. Subsequently, Seminis joined
Monsanto Corporation. The GM zucchini was modified with coat protein
genes from Zucchini Yellow Mosaic Virus and Watermelon Mosaic Virus 2.
The GM squash and Zucchini were not well supported by farmers in the
United states because viruses such as cucumber mosaic virus were not
protected against by the GM C. pepo (6).
There is good evidence that the virus resistance genes are readily
spread to wild forms of C. pepo. Spencer and Snow (7) showed that GM
yellow squash , derived by crossing with GM crookneck squash (
essentially the same kind of cross that produced GM Zucchini) readily
pollinated wild C. pepo to produce virus resistant wild (weedy) squash.
A commercial C. pepo squash bearing coat protein genes for the two
viruses in the original GM squash along with a coat protein gene for
Cucumber Mosaic Virus was found to make hybrids with the wild squash C.
pepo subspecies ovifera var texana . The hybrids grew more vigorously
and produced more seed than the wild plants from which they were derived
It seems clear that GM virus resistant squash are a blessing to wild and
weedy relatives of the GM squash. In the case of the illegal releases of
GM Zucchini in Germany it was suggested that the GM plants were grown in
a green house. As a rule, greenhouses ventilation systems readily allow
movement of pollinating insects between the greenhouse and nearby
fields. It is safest to presume that the viral transgenes have
contributed to the production of better wild and weedy squash in the
fields of Germany.
1. Quemada,H. and Tricoli,D. Petition for determination of regulatory
status of Cucurbiata pepo L. cultivar YC77E ZW-20 Petitions of
Nonregulated Status Granted or Pending by Aphis 1992
2. Smith,B. The initial domestication of Cucurbita pepo in the Americas
10,000 years ago Science 1997, 276, 932-4
3. Diez,M,Pico,B. and Nuez,F. Cucurbit genetic resources in Europe
Future Harvest 2002 http://www.ipgri.cgiar.org/publications/pdf/835.pdf
4. Paris,H. and Nelson,H. Seed dimensions in the subspecies and cultivar
groups of Cucurbita pepo Genetic Resources and Crop Evolution 2003,50,615-25
5. Gaba,V,Zelcer,A. and Gal-On ,A. Cucurbit biotechnology-The importance
of virus resistance In Vitro Cell Dev Biol-plant 204,40, 346-58
6. Public Issues Education Project Am I eating GE squash or zucchini?
7. Spencer,L. and Snow,J. Fecundity of transgenic wild crop hybrids o of
Cucurbita pepo: Implications for crop to wild gene flow. Heredity 2001
8. Fuchs M, Chirco EM, McFerson and Gonsalves D. Comparative fitness of
a wild squash species and three generations of hybrids between wild x
virus-resistant transgenic squash. Environ Biosafety Res. 2004
9. Fuchs M, Chirco EM and Gonsalves D. Movement of coat protein genes
from a commercial virus-resistant transgenic squash into a wild
relative. Environ Biosafety Res. 2004 Jan-Mar;3(1):5-16.
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